splice: Apply generic position and size checks to each write

We need to check the position and size of file writes against various
limits, using generic_write_check().  This was not being done for
the splice write path.  It was fixed upstream by commit 8d0207652cbe
("->splice_write() via ->write_iter()") but we can't apply that.

CVE-2014-7822

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index d20d64c..0de24a2 100644 (file)
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2468,9 +2468,7 @@ static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
        struct address_space *mapping = out->f_mapping;
        struct inode *inode = mapping->host;
        struct splice_desc sd = {
-               .total_len = len,
                .flags = flags,
-               .pos = *ppos,
                .u.file = out,
        };
 
@@ -2480,6 +2478,12 @@ static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
                        out->f_path.dentry->d_name.len,
                        out->f_path.dentry->d_name.name, len);
 
+       ret = generic_write_checks(out, ppos, &len, 0);
+       if (ret)
+               return ret;
+       sd.total_len = len;
+       sd.pos = *ppos;
+
        if (pipe->inode)
                mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_PARENT);
 

diff --git a/fs/splice.c b/fs/splice.c
index 714471d..34c2b2b 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1013,13 +1013,17 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
        struct address_space *mapping = out->f_mapping;
        struct inode *inode = mapping->host;
        struct splice_desc sd = {
-               .total_len = len,
                .flags = flags,
-               .pos = *ppos,
                .u.file = out,
        };
        ssize_t ret;
 
+       ret = generic_write_checks(out, ppos, &len, S_ISBLK(inode->i_mode));
+       if (ret)
+               return ret;
+       sd.total_len = len;
+       sd.pos = *ppos;
+
        pipe_lock(pipe);
 
        splice_from_pipe_begin(&sd);